config/seata-config-core/src/main/java/io/seata/config/ConfigurationChangeListener.java
<reponame>tyc1210/seata-1/*
 *  Copyright 1999-2019 Seata.io Group.
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package io.seata.config;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

import io.seata.common.thread.NamedThreadFactory;

/**
 * The interface Configuration change listener.
 *
 * @author slievrly
 */
public interface ConfigurationChangeListener {

    /**
     * The constant CORE_LISTENER_THREAD.
     */
    int CORE_LISTENER_THREAD = 1;
    /**
     * The constant MAX_LISTENER_THREAD.
     */
    int MAX_LISTENER_THREAD = 1;
    /**
     * The constant EXECUTOR_SERVICE.
     */
    ExecutorService EXECUTOR_SERVICE = new ThreadPoolExecutor(CORE_LISTENER_THREAD, MAX_LISTENER_THREAD,
        Integer.MAX_VALUE, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<>(),
        new NamedThreadFactory("configListenerOperate", MAX_LISTENER_THREAD));

    /**
     * Process.
     *
     * @param event the event
     */
    void onChangeEvent(ConfigurationChangeEvent event);

    /**
     * On process event.
     *
     * @param event the event
     */
    default void onProcessEvent(ConfigurationChangeEvent event) {
        getExecutorService().submit(() -> {
            beforeEvent();
            onChangeEvent(event);
            afterEvent();
        });
    }

    /**
     * On shut down.
     */
    default void onShutDown() {
        getExecutorService().shutdownNow();
    }

    /**
     * Gets executor service.
     *
     * @return the executor service
     */
    default ExecutorService getExecutorService() {
        return EXECUTOR_SERVICE;
    }

    /**
     * Before event.
     */
    default void beforeEvent() {

    }

    /**
     * After event.
     */
    default void afterEvent() {

    }
}
